How to Configure Basic Bandwidth Shaping Policing on Cisco Fortigate for ISP Connection

When Internet Service Providers (ISP) have a new internet link provisioned, very often they have shaping rules on their NTU to regulate internet traffic at promised rate. If your firewall/router/switch is sending excessive traffic than promised rate, the packet will be dropped, then ends up with suboptimal performance and slow internet speed. This post is to list out the basic bandwidth shaping or policing rule on Cisco or Fortigate devices.

Telstra Internet Direct – Optimising Network Performance

The below example notice is given by Telstra when they provide the public IP information:

For your Telstra Internet Direct Adapt service to operate at the maximum rate, you are advised to shape your outbound traffic. Within our network we police the rate of your service at your purchased speed. For example, on a 50 Mbps service you should rate limit your outbound traffic to 50 Mbps or below. Due to the differences between routers from different vendors you may need to adjust the burst rate of this feature to find a value that does not exceed our policer. Failure to apply shaping outbound may result in below par speeds being achieved. 

Bandwidth Limiting / Shaping on Cisco Switch or Router

The below example is to rate-limit outbound traffic at 400Mbps

conf t

policy-map Shaping
 class class-default
    shape average 398000000

interface te2/1/4
 description **ISP_link**
 switchport mode access
 switchport access vlan 4
 service-policy output Shaping


Check Shaping interface status

ICTFellaSW01#show policy-map interface

  Service-policy output: Shaping

    Class-map: class-default (match-any)  
      0 packets
      Match: any 
      (total drops) 11664895
      (bytes output) 1314982020
      shape (average) cir 398000000, bc 1592000, be 1592000
      target shape rate 398000000

Fortinet Fortigate Firewall WAN port

Estimated bandwidth on WAN port is mostly used for calculation of traffic control in SD-WAN rules, such as spillover

Traffic Shaping using Outbound shaping profile

Useful Links

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